The San Onofre Nuclear Generating Station is seen from the beach along San Onofre State Beach on March 15, 2012, south of San Clemente, Calif. (David McNew/Getty Images)

But the decision to shut down a plant that provided about a fifth of San Diego and southern Orange County’s power is leading to other challenges: an increase in greenhouse gas emissions; massive layoffs; and the question of how to store spent nuclear fuel.

The Southern California power plant has been out of commission since January 2012, when a radiation leak revealed major internal problems in its tubing system. San Onofre’s Units 2 and 3 produced 2,200 megawatts of electricity – enough to power 1.4 million homes, according to Southern California Edison Vice President David Mead. The utility made the decision to permanently shutter the power plant last month.

Less Nuclear Means More Greenhouse Gases

Testifying in front of the state Senate’s Energy Utilities and Communication Committee Wednesday morning, Mead told lawmakers that power plants fueled by natural gas have bridged Southern California’s electricity-generating gap since San Onofre went offline. That has led to an increase in greenhouse gas emissions. While 50 percent of SCE’s electricity came from carbon dioxide-free sources (nuclear, hydroelectric and renewable) in 2011, that number dropped to 30 percent in 2012. This comes at a time when California is trying to reduce greenhouse gas emissions to 1990 levels by the end of the decade.

And as greenhouse gas emissions go up, SCE’s staffing levels will drop. “Right now it looks like we will be going from the current amount of 1,500 employees down to 400 eventually,” Mead said. “We’re in the middle of a dramatic staffing reduction right now that’s going to get us to 600 employees by September.”Long-Term Vulnerabilities

San Diego Gas & Electric vice president Jim Avery told lawmakers his utility responded by increasing output at its other power plants, which had been operating at only 41 percent capacity. “When San Onofre went offline those numbers increased to about 65 percent. That increase in energy that came out of those combined-cycle power plants created enough energy to displace 80 percent of the loss of San Onofre within the San Diego basin.”

But state regulators warned the closure creates long-term vulnerabilities, especially as California utilities rely more and more on renewable energy. “It takes a portfolio of different types of resources to meet all the needs that we have,” said California Public Utilities Commissioner Mike Florio. “Nowhere in the constitution are we given the ability to dictate when the sun’s going to shine or when the wind’s going to blow. So that is a real limitation on renewables.”

California’s Independent System Operator, which oversees the state’s electricity grid, is studying how to replace San Onofre’s lost power, and expects to release a report in late 2013 or early next year.